Hitherto, there have been known the following processes for the transformation of an organic polymer into an epoxidized organic polymer through oxidation: (1) a process in which percarboxylic acid is prepared in advance by reacting hydrogen peroxide with a lower carboxylic acid such as formic acid or acetic acid, and the percarboxylic acid is added to the reaction system as an epoxidizing agent so as to cause an epoxidizing reaction in the presence or absence of a solvent, and (2) a process in which epoxidizing reaction is caused by use of hydrogen peroxide in the presence of a catalyst such as an osmate or tungstic acid, and a solvent. These processes are both characterized in that an organic polymer to be epoxidized is dissolved in a solvent so as to carry out epoxidized reaction effectively, and the synthesized epoxidized organic polymer is recovered by desolvating treatment.
According to these processes, if the organic polymer to be epoxidized is in a liquid state or paste state, the resultant epoxidized organic polymer is also in a liquid or paste state, and therefore, the latter can be readily recovered by a desolvating procedure. However, if in a solid state, the reaction mixture is subjected to a desolvating procedure to cause the epoxidized organic polymer to precipitate in a solid state, and this precipitation and recovering operation for the epoxidized product is very difficult. Particularly when the organic polymer to be epoxidized is a rubber polymer, the synthesized epoxidized organic polymer becomes viscous to considerably reduce workability.
Under the above circumstances, a process for producing epoxidized organic polymers which involves a simplified post-treatment is desired.
In the meantime, Japanese Patent Application Laid-Open (kokai) No. 60-168750 discloses a thermoplastic polyester which contains epoxidized EPDM as an agent to improve impact resistance. Yet, improvement of impact resistance of general thermoplastic resins, including thermoplastic polyesters, is still desired.
Conventional primers for polypropylene are described, for example, in Japanese Patent Publication (kokoku) No. 63-54312, which discloses primers obtained through graft-polymerization of maleic anhydride to a chlorinated polypropylene resin; and in Japanese Patent Publication (kokoku) No. 62-21027, which discloses primers obtained through graft-polymerization of maleic anhydride to a polypropylene/ethylene copolymer. Moreover, Japanese Patent Application Laid-Open (kokai) No. 4-258643 discloses primers having improved adhesion, which is attained by co-use of a chlorinated polypropylene resin and any one of a sorbitol epoxy resin, glycol-ether-type epoxy resin, or a bisphenol epoxy resin. In addition, Japanese Patent Application Laid-Open (kokai) No. 7-150107 discloses primers containing a butadiene epoxy resin in a graft polymer formed of chlorinated polypropylene and maleic anhydride.
However, of the above-mentioned primer compositions, those disclosed in Japanese Patent Publication (kokoku) Nos. 63-54312 and 62-21027 and Japanese Patent Application Laid-Open (kokai) No. 4-258643 do not exhibit sufficient adhesive properties when they are tested for waterproofness and antihygroscopic properties, unless they are pre-treated by cleaning with trichloroethane vapor. The primer compositions disclosed in Japanese Patent Application Laid-Open (kokai) No. 7-150107 also has the same problem, if there remain mold releasing agents used at the time of molding. Such a case requires wiping with a solvent such as isopropyl alcohol or toluene or similar steps. Washing with aqueous substances in turn requires a facility enabling many cleaning steps, such as so-called power-wash, which results in considerably high facility costs and cleaning costs.
Regarding techniques related to unvulcanized rubber compositions, Japanese Patent Application Laid-Open (kokai) No. 3-161329 discloses a process for producing a rubber composition suitable for weather strips. The technique disclosed in that publication is characterized by the following. An adhesive layer of a nitrile rubber/EPDM blend is formed on the glass portion of the main body of glassrun made of EPDM. Upon formation of the adhesive layer, an extruder that extrudes a glassrun main body and another extruder that extrudes an adhesive layer are connected to a multi-color extrusion head, to thereby effect co-extrusion. Subsequently, the adhesive layer on the glass portion of the glassrun main body of the thus-extruded molding is coated with a urethane paint by way of a conventional method such as flow coating or brushing, and then vulcanized.
However, since the process disclosed in that publication employs independent extruders for performing extrusion of the glass portion of the glassrun main body and extrusion of the adhesive layer, facility costs rise. Moreover, since a urethane paint is required to be applied through a customary method onto the extrudate that has left the extruder and not yet been vulcanized, the coating means cannot contact the glassrun main body, and therefore, particularly in the case in which the molded product has a cross section that is difficult to unfold, there exist portions that cannot be easily coated. Independently, Japanese Patent Application Laid-Open (kokai) No. 5-237448 discloses a technique for improving coating properties by the incorporation of EPDM and polyglycidyl methacrylate into a rubber composition. However, there is desired development of a technique that uses fewer ingredients, eliminates use of polyglycidyl methacrylate, and still provides excellently improved coating properties.